Aspect Ratio Calculator

Resize an image, video or screen while keeping its proportions, or reduce any width and height to its simplest aspect ratio.

Pixels, inches or any unit

How to use the Aspect Ratio Calculator

  1. Choose the what do you want to do?.
  2. Enter the ratio width.
  3. Enter the ratio height.
  4. Enter the width – Pixels, inches or any unit.
  5. Enter the height.
  6. Press Calculate. The result updates automatically as you type.

About the Aspect Ratio Calculator

The aspect ratio is the shape of a picture: its width compared with its height. Keeping it fixed when you resize avoids stretched faces in video, black bars on a TV and distorted thumbnails on websites and social media.

Some ratios are marketing names rather than exact values. "21:9" ultrawide monitors are really 64:27 (2560 × 1080) or 43:18 (3440 × 1440), and cinema "scope" is about 2.39:1. Phone screens such as 2400 × 1080 reduce to 20:9. When a ratio does not simplify neatly, the calculator shows it as a decimal against 1.

Formula

Height = Width × (Ratio height ÷ Ratio width)
Width = Height × (Ratio width ÷ Ratio height)
Simplified ratio = (W ÷ GCD) : (H ÷ GCD)

GCD is the greatest common divisor. For 1920 × 1080 the GCD is 120, giving 16:9. For a 1280-pixel-wide 16:9 frame, the height is 1280 × 9 ÷ 16 = 720.

Example calculation

Using the default values:

  • What do you want to do? = Find the height for a width
  • Ratio width = 16
  • Ratio height = 9
  • Width = 1280

the calculator returns:

  • Missing dimension: 720
  • Dimensions: 1,280 × 720
  • Aspect ratio: 16:9
  • Decimal ratio: 1.778 : 1
  • Common name: 16:9 widescreen HD

Frequently asked questions

What is the aspect ratio of 1920 × 1080?

16:9, because both numbers divide by 120 to give 16 and 9.

How do I find the height for 16:9?

Multiply the width by 9 and divide by 16. A 3840-pixel-wide image is 2160 pixels tall.

Is 21:9 really 21:9?

No. 21:9 is a rounded label. Common ultrawide panels are 64:27 (about 2.37:1) or 43:18 (about 2.39:1).

What aspect ratio is 4K?

Consumer 4K UHD (3840 × 2160) is 16:9. Cinema DCI 4K (4096 × 2160) is about 1.90:1.

Last updated: · Category: TV & Video calculators

Related calculators